Lecture 28: Connective tissue Flashcards
Components of Connective tissue
1) Cells (transient and permanent)
2) Extracellular matrix (ECM) = fibers, ground substance
- Supplied by blood, lymphatic vessels and nerves
- Alter these three components to make different types of connective tissue
Why is connective tissue important
1) Supports (forms the stroma of the organs)
2) Repairs
3) Defense (immune function)
4) Nutrition (storage and transport)
Embryonic connective tissue
1) Mesenchymal Connective tissue
-Contains mesenchymal cells, stem cells, tapered spindle appearance
-Sparsely arranged reticular fibers (Round)
-Abundant ground substance (GAG’s)
Function: Gives rise to other connective tissues
2) Mucous Connective tissue
- Contains mesenchymal cells, ground substance = MORE, Hyaluronan, gelatinous consistency to the matrix)
- Umbilical chord
- Provides fetus with protection and blood
- FIbers = star shaped
Loose Connective tissue
1) Cell > fibers
2) Rich blood supply: allows oxy and co2 exchange, diffusion of hormones and growth factors
(Blood vessels can move easier through loose connective tissue bc less fibers, fibers = immovable)
-Epithelium needs blood supply, so under it will always be loose connective tissue
3) Location: Beneath epithelia linings, lamina propria, around grandular epithelium
Dense Irregular Connective tissue
1) Fibers > Cells (than loose tissue)
2) No orientation of collagen fibers (resistance to stress in all directions
3) Organs capsules, periosteum, dermis
Dense regular Connective tissue
1) Specific (regular) orientation of collagen fibers
2) Tensile strength
Components
1) Fibroblasts = tendon: tendinocytes
2) Collagen fibers (type 1) = gives strength
Structure of tendon
1) Epitendineum: Covers entire tendon
2) Peritendineum: Covering around a group of fascicles
3) Endotendineum: Connective tissue covering around a group of fibers
Elastic tissue
1) Elastic fibers:
- Core of elastin + fibrillin microfibrils
- REQUIRES ORECEIN, RESOCIN, OR VERHOEFF’S staining
- Connected to desmosine and isodesmosine
- USED for stretch
2) Ligamentum flavum, vocal ligament, suspensory ligament of the penis
White Adipose Connective tissue
- Cells = large
- Nucleus = peripheral
- Lipid droplet= one
- Pale staining = negative profiling
- Functions = fat storage
Brown Adipose Connective tissue
- Cells = smaller than white
- Nucelus= central
- Lipid droplets= many
- Function= Energy release
What are the types of specialized connective tissue?
1) Cartilage
2) Bone
3) Blood
Ehlers-Danlos Syndrome
-Abnormal collagen productions bc of mutation in genes encoding the alpha-chains in various collagens (Enzyme deficiency)
-Effects Collagen Type III or Type V Symptoms Type III: -Def Col3A1 gene 1) Fragile skin and vascular cell walls 2) Early morbidity and mortality (bc vessels and organs rupture)
Symptoms Type V:
- Def Col5A1 and COl5A2
1) Hyper mobility of joints/digits
2) Hyperextensible skin
Marfan’s Syndrome
-Decreased elastic fibrillin (Fibrillin gene)
Symtoms:
1) Tall stature
2) Long limbs, fingers, toes
-Cardiovascular manifestations = aortic aneurysm and mitral valve prolapse
Fibrosis, keloids
Due to increased collagen
- Hypertrophic scar = Scars when more raids than normals, but within original wound boundary
- Keloid scar = Extending into surrounding tissue
Scurvy
Decreased collagen (vitamin C) = decreased stability and strength of collagen
Symptoms:
-Bleeding gums, hemorrhages, poor wound healing
Anaphylactic shock
Increased mast cell release of histamine
Edema
Swelling due to increased tissue fluid
Collagen Fibers
Elastic Fibers
Reticular fibers
Collagen Fibers:
-Thicker, Do not branch, intersect
Elastic Fibers:
-Thinner, do not branch, intersect (allow strength)
Reticular Fibers:
- Type III Collagen
- Function: Filters blood, allows large volume changes while maintaining structural integrity
- Found: (Liver, spleen)
- Short, thin, highly BRANCHING
- Components:
1) Fibroblasts
2) Argyrophilic reticular fibers
Function:
1) Supports myeloid and lymphoid organs (Bone marrow, lymph nodes, spleen)
2) Liver
3) Endocrine tissue
4) Nerve tissue
Hydroxy proline
Hydroxy lysine
Hydroxy proline
-Gives more Hydrogen bonding = more tight winding triple helix
Hydroxyl lysine
-Useful bc has OH, can add a sugar = O-linked-glycosylation
-Both involved in hydroxylation, need Vit C to work
Osteogenesis Imperfecta (OI)
- Brittle bones disease (Autosomal dominant)
- Mutation in COL1A1 and COL1A2= def in collagen
- Displacement of glycine in bone collagen = improper formation and stability of collagen triple-helix
Types:
1) OI Type I: Osteogenesis Imperfecta Tarda
- Mildest form
- Long bone fractures in early childhood
- Hearing loss
- Blue sclera
2) OI Type II: Osteogenesis Imperfecta Congenita
- Death in utero due to respiratory problems
- Underdeveloped lungs
- Fragile rib cage
3/4) OI Type III and IV:
- Severe scoliosis
- Bone malformations
- Dentiogenesis imperfecta –> discolored/weak teeth
Elastin
Similarities to collagen:
- Contains glycine, lysine, proline
- Secreted as tropoelastin
- Some hydroxyproline (less tho)
Differences from collagen:
1) No hydrozylysine
2) Not glycosylated
-Assembled into elastin fibers w crosslinking
Fibrillin
- Made of elastin and microfibrils
- Deficiency = Marfans syndrome (Mutation FBN1-gene)
Symp Marfans:
- aortic aneurysms
- Tall/long bodies/fingers
- Sunken chest
- lens issues
